Circuit-interrupter



K. C. RANDALL.

CIRCUIT INTERRUPTEH.

APPLICATION.FILED NOV. 19. 1917.

Patented J an. 13, 1920 INVENTOR WITNESSE m K ar/ 0. Randfl/ ATTORNEY l'lNlI ElU @TAflTE AEN FIQE.

Kenn CJBANDALL, or nnenwoon PARK, PENNSYLVANIA, ASSI GNOR 'ro WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA.

Application filed November 19, 1917.

To all whom it may concern:

it known that I, KARL U. RANDALL, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Circuit-Interrupters, of which the following is a. specification.

My invention relates to circuit interrupters and particularly to means for limiting current traversing the same.

One object of my invention is to provide an independent means for limiting the current traversing" a circuit interrupter when a predetermined excessive overload traverses the circuit to which it is connected.

Another object of my invention is to provlde means for 'so limiting the current travers ng a circuit, when an excessive overload obtains thereon, that an interrupter having a relatively small capacity may he used therein.

A further object of invention is to provide a device of the above indicated character that shall be simple and inexpensive to construct and effective in its operation.

In practising my invention, I provide a circuit interrupter, an overload tripping device therefor. a. currentlimiting resistor and a fuse for normally short circuiting the resistor. The fuse is of such characteristic that it will rupture when a relatively large overload traverses the circuit to thereby per- .mit the interrupter to safely interrupt the circuit. Visible or audible means is also provided indicating the rupture of the fuse.

n the accompanying drawings, Figure 1 is a diagrammatic View of an electrical circuit embodying my invention, and Figs. 2 and 3 are diagrammatic views of electrical circuits embodying modified forms of my tion I -c rical circuit 1 comprises an interand a current-limiting device, such 1r 3. A series transformer 4- is opconnected between the circuit 1 and the winding 5 of a definite time-innit overload relay 6. A tripping electromagnet 7 operatively connected to a source 8 electroihotive force and the stationary contact members 9 of the relay (3 and is adapted to be energized a definite interval of time after a predetermined overload traverses the Specification of Letters Patent.

CIRCUIT-INTERRUPTER.

Patented Jan.13, 1920. Serial No. 202,735.

circuit 1. A fuse 10 is connectedin shunt relation to the resistor 3, and a signal device 11 is connected in shunt relation to a portion of the resistor.

The fuse 10 has such characteristics that it will not be rupturi d under such ordinary overload conditions as can be adequately handled by the interrupter However, if

relatively large overload traverses the circuit l, the fuse 10 is adapted to be ruptured to thereby cause the resistor to so limit the current traversing the interrupter 2 that, when the interrupter i2 is tripped, it will not. be destroyed by reason of the excessive overload thereon. In order to insure that the interrupter 2 shall not be tripped before the load is limitted to a safe value, the relay (3 is provided and adapted to delay the tripping of the interrupter a predetermined definite interval of time after the occurrence of the overload. When the fuse 10 is blown, a sufiicient drop in voltage will obtain acrossa portion of the resistor 3 to effect the op-' eration of the signal device 11' for the purpose of indicating, to a station operator, that the fuse 10 has been blown.

In Fig. 2 of the drawings, a fuse 12 is connected in shunt relation to the resistor 3 and is provided with a spring-actuated movable contact member 13 that is adapted to be released for the purpose of engaging stationary contact members 14 when the fuse is ruptured. Thecontact members 14 constitute "the terminals of a circuit 15 comprising a signal device 16 and a source 17 of electromotive force. The signal device 16 will remain operative irrespective of the tripping of the interrupter 2 and, conscquently, serves as a positive indicator of the rupture of the fuse 12.

In Fig. 3 of the drawings, the tripping electro-n'iagnet 23 of the interrupter 2 is operatively connected to a series trans former 18 and to the stationary contact members 19 of a relay 2(). The winding 21 of the relay is connected in series with the circuit 1 and is adapted to hold its m0vable contact members 22 in engagement with the stationary contact members 19 when a predetern'iined overload traverses the circuit 1. The stationary contact members 19 and movable contact members 22 constitute a short-circuiting device for the electromagnet 23, to thereby prevent the interrupter 2 'lar structures illustrated,

from being tripped When the overload traversing the circuit 1 exceeds a predetermined value. However, when a suiiiciently high overload traverses the circuit 1 to rupture the fuse 10, the resistor 3 will so limit the current traversing the circuit 1 that the movable iontact member 22 of the relay 20 will be disengaged from the stationary contact members 19 to permit the electroinag'net 23 to trip the interrupter 2 after an interval of time, as controlled by a dash-pot 24-. By such an arrangement. an interrupter 2- of such size as to interrupt ordinary overloads may be safely used to interrupt relatively high overloads.

ldy invention is not limited to the particuas it may be variously modified without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention:

1. In an electric circuit. the combination with a. circuit interrupter and an overload trippin device therefor, of a current-limiting device connected in circuit with the in terrupter, and means for causingthe cur rent-limiting device to limit the current through the interru ner only when the load traversing the circuit exceeds the value for which the interrupter is intended.

2. In an electric circuit, the combination with a circuit interrupter having a normal overload interrupting capacity and an overload tripping device therefor, of a resistor connected in circuit With the interrupter, and means responsive to an excessive overload in the circuit for causing the resistor to limit the current traversing the interrupter only under predetermined excessive overload cond fions.

3. In an electric circuit, the combination with a circuit interrupter, of independent means for limiting the current traversing the interrupter only when the load traversm the circuit exceeds that value for which thg interrupter is intended.

4. In an electric circuit, the combination with a circuitinterrupter and an overload t ipping device therefor, of means for inserting a current-limiting device in circuit with the interrupter only when a predetermined overload traverses the circuit that is larger than the interrupting capacity of the lnterrupte 5. In an electric circuit, the combination with a circuit interrupter and means for trhJping the same when an overload traverses the circuit, of a resistor connected in series with the interrupter, and a fuse connected in shunt relation to the resistor and adapted to be ruptured only When a predetermined overload traverses the circuit that is larger than the interrupting capacity of the interrupter.

6. In an electric circuit, the combination with a circuit interrupter and means for tripping the same when an. overload trav erses the circuit, of a resistor connected in series with the interrupter, a fuse connected in shunt relation to the resistor and adapted to be ruptured only when an over load larger than that intended to be interrupted by the"interrupter traverses the circuit, and means for indicating the rupture of the fuse.

'7. In an electric circuit, the combination with a circuit interrupter, of independent means adapted to be operatively'associated u 1th the interrupter only when a predetermined load traverses the circuit to reduce the load required to be interrupted by the ii' terrupter to a value for which the inter rupter is intended.

In testimony whereof, if have hereunto subgcribed my name this 31st day f Get, 191

KARL centennial 

